Process for the manufacture of a band saw

ABSTRACT

A novel process for the manufacture of a metal- or wood-cutting band saw having a uniform structure and mechanical strength and sufficiently flexible to pass over two wheels on a conventional sawing equipment without breaking along the line of weld in the course of metal- or wood-cutting operations. For the manufacture of such a band saw, a series of saw teeth are formed on one edge of cutting edge of an elongated steel band adapted for serving as a band saw. The steel band is then cut to a predetermined length and the cut material is welded at the two ends directly without any solder therebetween. The steel band saw is then quenched and tempered as a whole to obtain an even temper, and the front or cutting edge of the band is quenched and tempered as usual for hardening the saw teeth.

O United States Patent 1151 3,653,985 Funakubo [451 Apr. 4, 1972 s41 PROCESS FOR THE MANUFACTURE 1,921,039 8/1933 Remington ..76/112 OF A BAND SAW 2,445,150 7/1948 Mueller 148/127 X 3,089,945 5/1963 Connoy et al ..76/112 X Inventor: H I Z L WT 3- Fukasawa 3,315,548 4/1967 Anderson et al ..76/112 a a as 1, otou, 0 yo, apan 22 F1 d: D 3 196 Primary ExaminerCharles N. Lovell 1 l e cc 9 Attorney-Shlesinger, Fitzsimmons & Shlesinger [21] App1.N0.: 881,845

[57] ABSTRACT [30] Foreign Application Priority Data A novel process for the manufacture of a metalor woodcutting band saw having a uniform structure and mechanical Dec. 9, Japan F g and sufficiently flexible to p over two wheels on a conventional sawing equipment without breaking along the ..148/l27,76/11 :22,ll:gg: line of weld in the course of metal or wood cutting opera n tions [58] Field of Search ..29/95; 148/127, 34, 134, 143,

43 1; 7 1 2; 143 333; 219/1041, 043 10577 For the manufacture of such a hand saw, a series of saw teeth 105 7 73 01 04 121 are formed on one edge of cutting edge of an elongated steel band adapted for serving as a band saw. The steel band is then I 56] References Cited cut to a predetermined length and the cut material is welded at the two ends directly without any solder therebetween. The UNITED STATES PATENTS steel band saw is then quenched and tempered as a whole to obtain an even temper, and the front or cutting edge of the g z F t' l' i band is quenched and tempered as usual for hardening the saw erns em e a teem 1,217,095 2/1917 Krump ..148/147 X 1,503,310 7/1924 Ericson ..76/1 12 4 Claims, No Drawings I band saw.

PROCESS For: THE MANUFACTURE OF ABAND SAW This invention relates toa process for the manufacture of a f According to the conventional process for the manufacture of a band saw, a series of teeth or projections are formedon one edge of an elongated steel hoop or band of a suitable width adapted for serving as a band saw. The teeth or projections are given any desired set pattern and thefront orcutting edge of the hoop or band thus obtained is quenched and tempered ,in known manner for hardening the saw teeth. Thereafter, the hoop or band is cut to the desired length taking into account the distance. between the driving and driven solder therebetween so as to provide a continuous band and annealed along the line of weld.

The conventional process as above described may be diagrammatically represented by the following fl ow sheet:

Toothing operation and teeth-bending or -setting operation-quenching and tempering of the front or cutting edgecutting thehoop orband to the desired length-welding of the two ends of the cut materiaL-annealing the line of weld.

' The conventional process as above described, however, had

a serious drawback that the properties of steel were changed by the high welding heatand the band saw might notbe given the desirable flexibility and the uniform mechanical strength and tenacity particularly around the weld joint.

It was experienced that the band saw thus prepared was liable to break along the line of weld when subjected to the considerable tensile and bending moments accompanying the metalor wood-cutting operations. In effect, the process of welding even followed by annealing affects the structure of the band saw in such a way that the weld line is hardened and less ductile and, on the contrary, the parts adjoining thereto are considerably softened, as compared with the remaining parts of the saw band.

lt is the main object of the present invention to provide a novel process for the manufacture of a band sawprovided with an even temper and sufficiently flexible to withstand the considerable bending and tensile moments accompanying the metalor wood-cutting operations without the fear of breakage along the line of weld.

1n the copending patent application filed on the same date with the present application, Ser. No. 881,835, the present inventor has proposed a novel process for the manufacture of a band saw wherein the drawbacks inherent in the aforementioned conventional manufacturing process may be obviated to a more or less extent. According to the process disclosed by the aforesaid patent application, the band saw welded atits two ends is quenched and tempered in the order along the relatively narrow zone covering the line of weld and the narrow parts adjoining thereto. When processed in the aforementioned manner, the band saw may have uniform mechanical strength and the transition in the steel structure caused to exist in the course of welding may be obviated to a considerable extent. The process just described provides a marked improvement over the prior art in that the properties of the band saw proper to the steel material may be recovered at the line of weld, and thus the steel structure of the band saw may be rendered more uniform than in the case of the conventional prior process. However, it is a matter of difficulty that the band saw should be quenched and tempered precisely along the aforementioned relatively narrow zone of the band saw and consequently the desired uniform mechanical strength of the saw band could not always be attained by the process disclosed in the aforesaid patent application.

The present inventor has found that the desired properties of the band saw, viz., the flexibility and the tenacity of the uniform steel structure of the band saw, could be more advantageously attained when the band saw welded together directly at the two ends without any solder therebetween by resistance welding was quenched as a whole from a certain temperature and tempered as a whole from a certain temperature below thecritical temperatureo ftthe steelmaterial used for the manufacture of the band saw.

According to the present invention, the resistance welded product may be quenched from the temperature between 750 to 920 C. and the quenched product may be tempered in a relatively short periodof time by reheatingit (0 1116 temperature between 450 to 560 C., depending onthe properties of the steel materials used for the manufacture of the band saw.

Following the aforementioned heat-treatment, the front or cutting edge of the band saw is quenched and tempered in known manner for hardening the saw teeth.

The novelprocessaccording to the present invention may be diagrammatically represented by'the following flow sheet:

Cutting the hoop orband'to the desired lengthstoothing operation and the teeth-bending or -setting operation welding by a highheat of the two ends of the cut hoop or band into a continuous band without any solder therebetweenquenching and tempering of the thus obtained band as a wholeheat treating the front or cutting edge alone.

1n the following numerical examples, the band saw is adapted for cutting steel materials and carbon tool steel,alloy tool steel or high-speed tool steelwere usedfor the manufacture of the band saw. It is to be noted that any other materials may naturally be employed providing that the temperature used for the heat-treatmentshould be selected suitably according to the type of the materials employed for the manufactureof the band s aw. 1n the following examples, a series of saw teeth were formed on the cutting edge of the band by relying upon the conventional toothing operation and teeth-bending operation. The saw band thus provided with saw teeth and welded at its two ends was placed on a turntable andheated by passing over a flame or by using the so-called high-frequency heating. The band saw thus heated was then submerged in oil for quenching.

EXAMPLE I and teeth-bending or -setting operation. The two ends of the cut material were welded together by' using plasma jets.

The band saw thus obtained was heated as a whole to a temperature between 750 and 800 C. and quenched. Thereafter. the thus quenched band saw was tempered as a whole by heating it to a temperature between 450 and 500 C. Following the aforementioned heat-treatment, the front or cutting edge of the band saw alone was quenched and tempered as usual for hardening the saw'teeth to the desired degree.

The thus obtained product was cut transversely to the weld line and observed by using a microscope and an electron microscope. According to such observation, it was discovered that there was substantially no recognizable change in the steel structure adjacent to the jointed part and at the remaining parts of the band saw. it was also discovered as a result of a tensile test that the tensile strength of the band saw prepared by the present process was far superior to that of the band saw prepared by the prior process.

EXAMPLE 2 A band of carbon tool steel model SK7 (carbon content: 0.60 to 0.70 percent) Japanese Industrial Standard, as amended 1953 and 1956) was cut to a predetermined length and a series of saw teeth were formed on the one edge of the cut material by relying upon the conventional toothing operation and the teeth-bending or -setting operation. The two ends of the cut material were welded together by flash butt welding.

The band saw thus prepared was heated as a whole to a temperature between 780 and 820 C. and quenched. Thereafter, the thus quenched band saw was tempered as a whole for a relatively short period of time by heating it to a temperature between 450 and 500 C. Following the aforementioned heattreatment, the front or cutting edge of the band saw was alone quenched and tempered as usual for hardening the saw teeth.

The band saw thus obtained was cut transversely to the weld line and the section thus obtained was observed by using a microscope and an electron microscope. According to such observation, it was discovered that there was substantially no noticeable change in the steel structure of the band saw adjacent to the jointed part and at the remaining parts of the band saw. It was also discovered, as a result of a tensil test that the tensile strength of the band saw prepared by the present process was far superior to that of the band saw prepared by the prior processes.

EXAMPLE 3 A band of special tool steel model SKS-Sl (carbon content: 0.75 to 0.85 percent and nitrogen content: 1.30 to 2.00 percent Japanese Industrial Standard, as amended 1953 and 1956) was cut to a predetermined length and a series of saw teeth were formed on the one edge of the cut material by relying upon the conventional toothing operation and the teethbending or -setting operation. The two ends of the cut material were welded together by using plasma jets. The band saw thus obtained was then heated as a whole to a temperature around 850 C. and quenched. Thereafter, the thus quenched band saw was tempered as a whole by heating it to a temperature between 450 and 550 C. Following the aforementioned heattreatment, the front or cutting edge of the band saw alone was heat treated as usual for hardening the saw teeth.

The band saw thus obtained was cut transversely to the weld line and the section thus obtained was observed by using a microscope and an electron microscope. It was discovered by such observation that there was no noticeable change in the steel structure of the band saw adjacent to the jointed part and at the remaining parts of the saw band. It was also discovered as a result of the tensile test that the tensile strength of the band saw was far superior to that of the band saw prepared by the conventional processes.

EXAMPLE 4 A band of high-speed tool steel model SKl-l-9 (carbon content: 0.80 to 0.90 percent Japanese Industrial Standard, as amended 1953 and 1956) was cut to a predetermined length and a series of saw teeth were formed on the one edge of the cut material by relying upon the conventional toothing operation and the teeth-bending or -setting operation. The two ends of the cut material were welded together by flash butt welding.

The band saw thus obtained was heated as a whole to a temperature between 870 and 920 C. and quenched. Thereafter, the thus quenched band saw was tempered by heating it to a temperature between 550 and 560 C. Following the heattreatment as above described, the front or cutting edge of the band saw alone was quenched and tempered as usual for hardening the saw teeth.

The band saw thus obtained was cut transversely to the weld line and the section thus obtained was observed by using a microscope and an electron microscope. According to such observation, it was discovered that there was substantially no noticeable change in the steel structure of the band saw adjacent to the jointed part and at the remaining parts of the band saw. It was also discovered as a result of the tensile test that the tensile strength of the band saw prepared by the present process was far superior to that of the band saw prepared by the prior processes.

What is claimed is:

1. A process for the manufacture of a band saw comprising cutting a steel strip and forming therefrom an elongated hoop of a predetermined length; forming a series of teeth on one edge of the hoop; welding the two ends together without any solder therebetween into a continuous band; quenching the thus formed and welded band saw as a whole at a temperature between 750 and 920 C. tempering the band saw as a whole by reheating it to a temperature between 450 and 560; and

then successively quenching and tempering the front or cutting teeth edge alone.

2. A process for the manufacture of a band saw as claimed in claim 1, wherein carbon tool steel with a carbon content of 0.6 to 1.3 percent is used as the steel material and the welded product is quenched as a whole at a temperature between 780 and 850 C. and tempered as a whole at a temperature between 450 and 560 C., depending on the carbon content of the steel material.

3. A process for the manufacture of a band saw as claimed in claim 1, wherein special tool steel with a carbon content of 0.75 to 0.85 percent is used as the steel material and the welded product is quenched as a whole at the temperature around 850 C. and tempered as a whole at a temperature between 450 and 550 C.

4. A process for the manufacture of a band saw as claimed in claim 1, wherein high-speed tool steel with a carbon content of 0.80 to 0.90 percent is used as the steel material and the welded product is quenched as a whole at a temperature between 870 and 920 C. and tempered as a whole at a temperature between 550 and 560 C. 

2. A process for the manufacture of a band saw as claimed in claim 1, wherein carbon tool steel with a carbon content of 0.6 to 1.3 percent is used as the steel material and the welded product is quenched as a whole at a temperature between 780* and 850* C. and tempered as a whole at a temperature between 450* and 560* C., depending on the carbon content of the steel material.
 3. A process for the manufacture of a band saw as claimed in claim 1, wherein special tool steel with a carbon content of 0.75 to 0.85 percent is used as the steel material and the welded product is quenched as a whole at the temperature around 850* C. and tempered as a whole at a temperature between 450* and 550* C.
 4. A process for the manufacture of a band saw as claimed in claim 1, wherein high-speed tool steel with a carbon content of 0.80 to 0.90 percent is used as the steel material and the welded product is quenched as a whole at a temperature between 870* and 920* C. and tempered as a whole at a temperature between 550* and 560* C. 